Eight speed automatic transmission

ABSTRACT

An eight speed automatic transmission is provided having an input member, an output member, four planetary gear sets and five torque transmitting devices. Three of the planetary gear sets are simple and one planetary gear set is compound. Each of the plurality of planetary gear sets has first, second and third members: a sun gear, a ring gear and a planet carrier having a plurality of planet gears rotatably disposed thereon. Three of the torque transmitting devices are clutches and two of the devices are brakes. Eight embodiments of the transmission having different arrangements of the planetary gear sets, clutches and brakes are disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No. 12/050,470filed on Mar. 18, 2008, which claims the benefit of U.S. ProvisionalApplication No. 60/909,595 filed on Apr. 2, 2007. The disclosures of theabove applications are incorporated herein by reference.

FIELD

The invention relates to a multiple speed automatic transmission havingboth a plurality of planetary gear sets and torque transmitting devicesand more particularly to an eight speed automatic transmission havingfour planetary gear sets and a plurality of torque transmitting devices.

BACKGROUND

The statements in this section merely provide background informationrelated to the present disclosure and may or may not constitute priorart.

A typical multiple speed automatic transmission uses a combination ofplanetary gear arrangements, friction clutches and fixedinterconnections to achieve a plurality of gear ratios. The number andphysical arrangement of the planetary gear sets generally are dictatedby packaging, cost and desired speed ratios.

While current transmissions achieve their intended purpose, the need fornew and improved automatic transmission configuration which exhibitimproved performance, especially from the standpoints of efficiency,responsiveness and smoothness and improved packaging, primarily reducedsize and weight, is essentially constant. Accordingly, there is a needfor a cost-effective, compact and multi-speed transmission.

SUMMARY

An eight speed automatic transmission is provided having an inputmember, an output member, four planetary gear sets and five torquetransmitting devices. Three of the planetary gear sets are simple andone planetary gear set is compound. Each of the plurality of planetarygear sets has first, second and third members: a sun gear, a ring gearand a planet carrier having a plurality of planet gears rotatablydisposed thereon. Three of the torque transmitting devices are clutchesand two of the devices are brakes. Eight embodiments of the transmissionhaving different arrangements of the planetary gear sets, clutches andbrakes are disclosed.

It is thus an aspect of the present invention to provide an eight speedautomatic transmission.

It is another aspect of the present invention to provide an automatictransmission having four planetary gear sets.

It is another aspect of the present invention to provide an automatictransmission having three simple planetary gear sets and one compoundplanetary gear set.

It is another aspect of the present invention to provide an automatictransmission having four planetary gear sets and five torquetransmitting devices.

It is another aspect of the present invention to provide an automatictransmission having four planetary gear sets, three clutches and twobrakes.

It is another aspect of the present invention to provide an automatictransmission having three simple planetary gear sets, one compoundplanetary gear set, three clutches and two brakes.

Further areas of applicability will become apparent from the descriptionprovided herein. It should be understood that the description andspecific examples are intended for purposes of illustration only and arenot intended to limit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustration purposes only and arenot intended to limit the scope of the present disclosure in any way.

FIG. 1A is a lever diagram of an automatic transmission according to theprinciples of the present invention;

FIG. 1B is a truth table presenting the state of engagement of thevarious torque transmitting clutches and brakes in each of the availableforward and reverse speeds or gear ratios of the automatic transmissionillustrated in FIG. 1A;

FIG. 2 is a diagrammatic view of an automatic transmission according tothe principles of the present invention illustrating the zones of thetransmission;

FIG. 3A is a schematic diagram of a first embodiment of an automatictransmission according to the principles of the present invention;

FIG. 3B is a chart showing feasible locations of the clutch and brakecomponents for the first embodiment of the automatic transmission shownin FIG. 3A;

FIG. 4A is a schematic diagram of a second embodiment of an automatictransmission according to the principles of the present invention;

FIG. 4B is a chart showing feasible locations of the clutch and brakecomponents for the second embodiment of the automatic transmission shownin FIG. 4A;

FIG. 5A is a schematic diagram of a third embodiment of an automatictransmission according to the principles of the present invention;

FIG. 5B is a chart showing feasible locations of the clutch and brakecomponents for the third embodiment of the automatic transmission shownin FIG. 5A;

FIG. 6A is a schematic diagram of a fourth embodiment of an automatictransmission according to the principles of the present invention;

FIG. 6B is a chart showing feasible locations of the clutch and brakecomponents for the fourth embodiment of the automatic transmission shownin FIG. 6A;

FIG. 7A is a schematic diagram of a fifth embodiment of an automatictransmission according to the principles of the present invention;

FIG. 7B is a chart showing feasible locations of the clutch and brakecomponents for the fifth embodiment of the automatic transmission shownin FIG. 7A;

FIG. 8A is a schematic diagram of a sixth embodiment of an automatictransmission according to the principles of the present invention;

FIG. 8B is a chart showing feasible locations of the clutch and brakecomponents for the sixth embodiment of the automatic transmission shownin FIG. 8A;

FIG. 9A is a schematic diagram of a seventh embodiment of an automatictransmission according to the principles of the present invention;

FIG. 9B is a chart showing feasible locations of the clutch and brakecomponents for the seventh embodiment of the automatic transmissionshown in FIG. 9A.

FIG. 10A is a schematic diagram of an eighth embodiment of an automatictransmission according to the principles of the present invention; and

FIG. 10B is a chart showing feasible locations of the clutch and brakecomponents for the eighth embodiment of the automatic transmission shownin FIG. 10A.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is notintended to limit the present disclosure, application, or uses.

Referring now to FIGS. 1 and 2, in FIG. 1 an eight speed automatictransmission 10 according to the present invention is illustrated in alever diagram. A lever diagram is a schematic representation of thecomponents of an automatic transmission wherein the three fundamentalmechanical components of a planetary gear set, the sun gear, the planetgear carrier and the ring gear are represented by nodes. The relativelengths of the bars between the nodes of a given planetary gear setrepresent the ratios between the gears of the gear set. Mechanicalcouplings or interconnections between the nodes of the various planetarygear sets are illustrated by horizontal lines and torque transmittingdevices such as clutches and brakes are represented by nesting orinterleaved fingers. If the device is a brake, one side of the device isgrounded. Further explanation of the format, purpose and use of leverdiagrams can be found in SAE Paper 810102 entitled “The Lever Analogy: ANew Tool in Transmission Analysis” by Benford and Leising which is fullyincorporated herein by reference.

The transmission 10 includes an input shaft 12, a first simple planetarygear set 30, a second compound planetary gear set 40, a third simpleplanetary gear set 50, a fourth simple planetary gear set 60 and anoutput shaft 14. The planetary gear sets 30, 40, 50 and 60 are connectedbetween the input shaft 12 and the output shaft 14. The first simpleplanetary gear set 30 includes a first sun gear 32, a first planet gearcarrier 34 that rotatably supports a first plurality of pinion or planetgears 36 and a first ring gear 38. The second compound planetary gearset 40 includes a second sun gear 42, a second planet gear carrier 44that rotatably supports a second plurality of pairs of pinion or planetgears 46A and 46B and a second ring gear 48. The third simple planetarygear set 50 includes a third sun gear 52, a third planet gear carrier 54that rotatably supports a third plurality of pinion or planet gears 56and third a ring gear 58. The fourth simple planetary gear set 60includes a fourth sun gear 62, a fourth planet gear carrier 64 thatrotatably supports a fourth plurality of pinion or planet gears 66 and afourth ring gear 68.

The lever diagram of FIG. 1 illustrates the common or shared mechanicalcomponents and architecture of the various arrangements of the automatictransmission 10 illustrated in FIGS. 2A through 9A. Thus the followingexplanation of the interconnections between the planetary gear sets,clutches and brakes applies to the family of transmission arrangementsdisclosed herein. The input shaft 12 is always coupled to the firstplanet carrier 34 of the first planetary gear set 30. The output shaft14 is always coupled to and driven by the planet carrier 54 of the thirdplanetary gear set 50. A first shaft, quill or interconnecting member 72always couples the third ring gear 58 of the third planetary gear set 50to the fourth planet carrier 64 of the fourth planetary gear set 60. Asecond shaft, quill or interconnecting member 74 always couples thefirst sun gear 32 of the first planetary gear set 30 to the fourth sungear 62 of the fourth planetary gear set 60. A third shaft, quill orinterconnecting member 76 always couples the second sun gear 42 of thesecond compound planetary gear set 40 to the third sun gear 52 of thethird planetary gear set 50. A fourth shaft, quill or interconnectingmember 78 always couples the first ring gear 38 of the first planetarygear set 30 to the second planet carrier 44 of the second compoundplanetary gear set 40. A fifth shaft, quill or intermediate member 80 isconnected to the second sun gear 42 of the second planetary gear set 40.

The automatic transmission 10 includes a plurality of torquetransmitting mechanisms or devices including a first clutch 82, a secondclutch 84, a third clutch 86, a first brake 92 and a second brake 94.The first clutch 82 is always disposed between the first planet carrier34 of the first planetary gear set 30 and the input shaft 12 throughfifth shaft, quill or intermediate member 80 to the second sun gear 42of the second compound planetary gear set 40. The second clutch 84 isalways disposed between the first ring gear 38 of the first planetarygear set 30 and the second planet carrier 44 of the second compoundplanetary gear set 30 which are always coupled by the fourth shaft,quill or interconnecting member 78 and the second sun gear 42 of thesecond compound planetary gear set 40. A third clutch 86 is disposedbetween the second ring gear 48 of the second planetary gear set 40 andthe third ring gear 58 of the third planetary gear set 50 and the fourthplanet carrier 64 of the fourth planetary gear set 60 which are alwayscoupled by the first shaft, quill or intermediate member 72. The firstbrake 92 selectively connects the fourth sun gear 62 of the fourthplanetary gear set 60 and the first sun gear 32 of the first planetarygear set 30 which are always coupled by the second shaft, quill orintermediate member 74 to ground. The second brake 94 selectivelyconnects the fourth ring gear 68 of the fourth planetary gear set 60 toground

The transmission 10 is capable of transmitting torque from the inputshaft 12 to the output shaft 14 in eight forward speed and torque ratiosand one reverse speed and torque ratio as indicated in the truth tableof FIG. 1A. Each of the eight forward speed and torque ratios and thereverse speed and torque ratios is attained by engagement of acombination of three of the torque transmitting devices, i.e., the firstclutch 82, the second clutch 84, the third clutch 86, the first brake 92and the second brake 94.

With reference to the truth table of FIG. 1A, it will be appreciatedthat reverse gear is attained by activation or engagement of the firstbrake 92, the second brake 94 and the third clutch 86. Neutral isattained by activation or engagement of the first brake 92 and thesecond brake 94. It should be noted, however, that although the firstbrake 92 and the second brake 94 are engaged, they are not carryingtorque.

First gear is attained by activation or engagement of the first brake92, the second brake 94 and the first clutch 82. Second gear is attainedby activation or engagement of first brake 92, the second brake 94 andthe second clutch 84. Third gear is attained by activation or engagementof the second brake 94, the first clutch 82 and the second clutch 84.Fourth gear is attained by activation or engagement of the second brake94, the second clutch 84 and the third clutch 86. Fifth gear is attainedby activation or engagement of the second brake 94, the first clutch 82and the third clutch 86. Sixth gear is attained by activation orengagement of the first clutch 82, the second clutch 84 and the thirdclutch 86. Seventh gear is attained by activation or engagement of thefirst brake 92, the first clutch 82 and the third clutch 86. Eighth gearis attained by activation or engagement of the first brake 92, thesecond clutch 84 and the third clutch 86.

Referring now to FIG. 2, the automatic transmission 10 includes ahousing 20 including or defining a first or front end wall 22, a secondor rear end wall 24, and a third side wall 26. The third side wall 26interconnects the first end wall 22 and the second end wall 24 toprovide or define a space or cavity 28 in which the planetary gear sets30, 40, 50 and 60 and the torque transmitting mechanisms such as theclutches 82, 84 and 86 and the brakes 92 and 94 are located. Further,the space or cavity 28 has a plurality of Zones A, B, C, D, E, and F inwhich the clutches 82, 84 and 86 and the brakes 92 and 94 will bespecifically positioned in accordance with the preferred embodiments ofthe present invention.

As shown in FIG. 2 and throughout the several views, Zone A is definedby the area bounded on the left by the first end wall 22, on the rightby a planetary gear set FF in a first or forward position, on the bottomby a reference line “L” which is a line that is parallel and preferablycoaxial with the input shaft 12 and the output shaft 14 and on the topby a reference line “M” which is a line that extends along the outerdiameters of the planetary gear sets and is parallel to the referenceline ‘L.” Zone B is defined by the area bounded on the left by theplanetary gear set FF, on the right by a planetary gear set SM in asecond, middle position, radially outward by the reference line “M” andradially inward by the reference line “L.” Zone C is defined by the areabounded on the left by the planetary gear set SM, on the right by aplanetary gear set TM in a third, middle position, radially outward bythe reference line “M”, and radially inward by the reference line “L.”Zone D is defined by the area bounded on the left by the planetary gearset TM, on the right by a planetary gear set RF in a rear or fourthposition, radially outward by the reference line “M”, and radiallyinward by the reference line “L”. Zone E is defined by the area bounded:on the left by the planetary gear set RF, on the right by the second endwall 24, radially outward by the reference line “M”, and radially inwardby the reference line “L”. Zone F is defined by the area bounded on theleft by the first end wall 22, on the right by the second end wall 24,radially inward by the reference line “M” and radially outward by thethird side wall 26. Since the positions of the planetary gear sets 30,40, 50 and 60 will change within the transmission cavity 28 in thedifferent embodiments, the positions have been generically identified asFF, SM, TM and RF in FIG. 2 to define the Zones A, B, C, D, E and F.However, the Zones described above will not change and will remain thesame throughout the several views.

Referring now to FIG. 3A, a first embodiment of the automatictransmission 100 is shown. In the first embodiment of the automatictransmission 100, the planetary gear sets are longitudinally arranged inthe following order from left to right: 30-40-60-50. Specifically, thefirst planetary gear set 30 is disposed adjacent the first or front endwall 22 in the first position FF, the second compound planetary gear set40 is disposed adjacent the first planetary gear set 30 in the secondposition SM, the fourth planetary gear set 60 is disposed adjacent thesecond compound planetary gear set 40 in the third position TM and thethird planetary gear set 50 is disposed adjacent the second or rear endwall 24 in the fourth position RF. The torque transmitting devices areintentionally located within specific Zones in order to provideadvantages in overall transmission size, packaging efficiency, andreduced manufacturing complexity. In the first embodiment automatictransmission 100 shown in FIG. 3A, the first clutch 82 is disposed inZone A, the second clutch 84 is disposed in Zone B, the third clutch 86is disposed in Zone C and the first brake 92 and the second brake 94 aredisposed in Zone F.

However, the first embodiment of the automatic transmission 100 includesother arrangements where the first clutch 82, the second clutch 84, thethird clutch 86, the first brake 92 and the second brake 94 are disposedin other Zones. The feasible locations of the first clutch 82, thesecond clutch 84, the third clutch 86, the first brake 92 and the secondbrake 94 relative to the Zones are illustrated in the chart shown inFIG. 3B. An “X” in the chart indicates that the first embodiment of theautomatic transmission 100 comprehends locating the first clutch 82, thesecond clutch 84, the third clutch 86, the first brake 92 and the secondbrake 94 in the referenced Zone.

Referring now to FIG. 4A, a second embodiment of the automatictransmission 200 is shown. In the second embodiment of the automatictransmission 200, the planetary gear sets are longitudinally arranged inthe following order from left to right: 30-50-40-60. Specifically, thefirst planetary gear set 30 is disposed adjacent the first or front endwall 22 in the first position FF, the third planetary gear set 50 isdisposed adjacent the first planetary gear set 30 in the second positionSM, the second compound planetary gear set 40 is disposed adjacent thethird planetary gear set 50 in the third position TM and the fourthplanetary gear set 60 is disposed adjacent the second or rear end wall24 in the fourth position RF. The torque transmitting devices areintentionally located within specific Zones in order to provideadvantages in overall transmission size, packaging efficiency, andreduced manufacturing complexity. In the second embodiment automatictransmission 200 shown in FIG. 4A, the first clutch 82 and the secondclutch 84 are disposed in Zone B, the third clutch 86 is disposed inZone D, the first brake 92 is disposed in Zone F and the second brake 94is disposed in Zone E.

However, the second embodiment of the automatic transmission 200includes other arrangements where the first clutch 82, the second clutch84, the third clutch 86, the first brake 92 and the second brake 94 aredisposed in other Zones. The feasible locations of the first clutch 82,the second clutch 84, the third clutch 86, the first brake 92 and thesecond brake 94 relative to the Zones are illustrated in the chart shownin FIG. 4B. An “X” in the chart indicates that the second embodiment ofthe automatic transmission 200 comprehends locating the first clutch 82,the second clutch 84, the third clutch 86, the first brake 92 and thesecond brake 94 in the referenced Zone.

Referring now to FIG. 5A, a third embodiment of the automatictransmission 300 is shown. In the third embodiment of the automatictransmission 300, the planetary gear sets are longitudinally arranged inthe following order from left to right: 30-60-40-50. Specifically, thefirst planetary gear set 30 is disposed adjacent the first or front endwall 22 in the first position FF, the fourth planetary gear set 60 isdisposed adjacent the first planetary gear set 30 in the second positionSM, the second compound planetary gear set 40 is disposed adjacent thefourth planetary gear set 60 in the third position TM and the thirdplanetary gear set 50 is disposed adjacent the second or rear end wall24 in the fourth position RF. The torque transmitting devices areintentionally located within specific Zones in order to provideadvantages in overall transmission size, packaging efficiency, andreduced manufacturing complexity. In the third embodiment automatictransmission 300 shown in FIG. 5A, the first clutch 82 and the secondclutch 84 are disposed in Zone A, the third clutch 86 is disposed inZone D and the first brake 92 and the second brake 94 are disposed inZone F.

However, the third embodiment of the automatic transmission 300 includesother arrangements where the first clutch 82, the second clutch 84, thethird clutch 86, the first brake 92 and the second brake 94 are disposedin other Zones. The feasible locations of the first clutch 82, thesecond clutch 84, the third clutch 86, the first brake 92 and the secondbrake 94 relative to the Zones are illustrated in the chart shown inFIG. 5B. An “X” in the chart indicates that the third embodiment of theautomatic transmission 300 comprehends locating the first clutch 82, thesecond clutch 84, the third clutch 86, the first brake 92 and the secondbrake 94 in the referenced Zone.

Referring now to FIG. 6A, a fourth embodiment of the automatictransmission 400 is shown. In the fourth embodiment of the automatictransmission 400, the planetary gear sets are longitudinally arranged inthe following order from left to right: 40-30-60-50. Specifically, thesecond compound planetary gear set 40 is disposed adjacent the first orfront end wall 22 in the first position FF, the first planetary gear set30 is disposed adjacent the second compound planetary gear set 40 in thesecond position SM, the fourth planetary gear set 60 is disposedadjacent the first planetary gear set 30 in the third position TM andthe third planetary gear set 50 is disposed adjacent the second or rearend wall 24 in the fourth position RF. The torque transmitting devicesare intentionally located within specific Zones in order to provideadvantages in overall transmission size, packaging efficiency, andreduced manufacturing complexity. In the fourth embodiment automatictransmission 400 shown in FIG. 6A, the first clutch 82 and the secondclutch 84 are disposed in Zone A, the third clutch 86 is disposed inZone B and the first brake 92 and the second brake 94 are disposed inZone F.

However, the fourth embodiment of the automatic transmission 400includes other arrangements where the first clutch 82, the second clutch84, the third clutch 86, the first brake 92 and the second brake 94 aredisposed in other Zones. The feasible locations of the first clutch 82,the second clutch 84, the third clutch 86, the first brake 92 and thesecond brake 94 relative to the Zones are illustrated in the chart shownin FIG. 6B. An “X” in the chart indicates that the fourth embodiment ofthe automatic transmission 400 comprehends locating the first clutch 82,the second clutch 84, the third clutch 86, the first brake 92 and thesecond brake 94 in the referenced Zone.

Referring now to FIG. 7A, a fifth embodiment of the automatictransmission 500 is shown. In the fifth embodiment of the automatictransmission 500, the planetary gear sets are longitudinally arranged inthe following order from left to right: 40-50-30-60. Specifically, thesecond compound planetary gear set 40 is disposed adjacent the first orfront end wall 22 in the first position FF, the third planetary gear set50 is disposed adjacent the second compound planetary gear set 40 in thesecond position SM, the first planetary gear set 30 is disposed adjacentthe third planetary gear set 50 in the third position TM and the fourthplanetary gear set 60 is disposed adjacent the second or rear end wall24 in the fourth position RF. The torque transmitting devices areintentionally located within specific Zones in order to provideadvantages in overall transmission size, packaging efficiency, andreduced manufacturing complexity. In the fifth embodiment automatictransmission 500 shown in FIG. 7A, the first clutch 82 and the secondclutch 84 are disposed in Zone A, the third clutch 86 is disposed inZone B, the first brake 92 is disposed in Zone F and the second brake 94is disposed in Zone E.

However, the fifth embodiment of the automatic transmission 500 includesother arrangements where the first clutch 82, the second clutch 84, thethird clutch 86, the first brake 92 and the second brake 94 are disposedin other Zones. The feasible locations of the first clutch 82, thesecond clutch 84, the third clutch 86, the first brake 92 and the secondbrake 94 relative to the Zones are illustrated in the chart shown inFIG. 7B. An “X” in the chart indicates that the fifth embodiment of theautomatic transmission 500 comprehends locating the first clutch 82, thesecond clutch 84, the third clutch 86, the first brake 92 and the secondbrake 94 in the referenced Zone.

Referring now to FIG. 8A, a sixth embodiment of the automatictransmission 600 is shown. In the sixth embodiment of the automatictransmission 600, the planetary gear sets are longitudinally arranged inthe following order from left to right: 40-50-60-30. Specifically, thesecond compound planetary gear set 40 is disposed adjacent the first orfront end wall 22 in the first position FF, the third planetary gear set50 is disposed adjacent the second compound planetary gear set 40 in thesecond position SM, the fourth planetary gear set 60 is disposedadjacent the third planetary gear set 50 in the third position TM andthe first planetary gear set 30 is disposed adjacent the second or rearend wall 24 in the fourth position RF. The torque transmitting devicesare intentionally located within specific Zones in order to provideadvantages in overall transmission size, packaging efficiency, andreduced manufacturing complexity. In the sixth embodiment automatictransmission 600 shown in FIG. 8A, the first clutch 82 and the secondclutch 84 are disposed in Zone A, the third clutch 86 is disposed inZone B and the first brake 92 and the second brake 94 are disposed inZone E.

However, the sixth embodiment of the automatic transmission 600 includesother arrangements where the first clutch 82, the second clutch 84, thethird clutch 86, the first brake 92 and the second brake 94 are disposedin other Zones. The feasible locations of the first clutch 82, thesecond clutch 84, the third clutch 86, the first brake 92 and the secondbrake 94 relative to the Zones are illustrated in the chart shown inFIG. 8B. An “X” in the chart indicates that the sixth embodiment of theautomatic transmission 600 comprehends locating the first clutch 82, thesecond clutch 84, the third clutch 86, the first brake 92 and the secondbrake 94 in the referenced Zone.

Referring now to FIG. 9A, a seventh embodiment of the automatictransmission 700 is shown. In the seventh embodiment of the automatictransmission 700, the planetary gear sets are longitudinally arranged inthe following order from left to right: 60-30-40-50. Specifically, thefourth planetary gear set 60 is disposed adjacent the first or front endwall 22 in the first position FF, the first planetary gear set 30 isdisposed adjacent the fourth planetary gear set 60 in the secondposition SM, the second compound planetary gear set 40 is disposedadjacent the first planetary gear set 30 in the third position TM andthe third planetary gear set 50 is disposed adjacent the second or rearend wall 24 in the fourth position RF. The torque transmitting devicesare intentionally located within specific Zones in order to provideadvantages in overall transmission size, packaging efficiency, andreduced manufacturing complexity. In the seventh embodiment automatictransmission 700 shown in FIG. 9A, the first clutch 82 and the secondclutch 84 are disposed in Zone C, the third clutch 86 is disposed inZone D and the first brake 92 and the second brake 94 are disposed inZone A.

However, the seventh embodiment of the automatic transmission 700includes other arrangements where the first clutch 82, the second clutch84, the third clutch 86, the first brake 92 and the second brake 94 aredisposed in other Zones. The feasible locations of the first clutch 82,the second clutch 84, the third clutch 86, the first brake 92 and thesecond brake 94 relative to the Zones are illustrated in the chart shownin FIG. 9B. An “X” in the chart indicates that the seventh embodiment ofthe automatic transmission 700 comprehends locating the first clutch 82,the second clutch 84, the third clutch 86, the first brake 92 and thesecond brake 94 in the referenced Zone.

Referring now to FIG. 10A, an eighth embodiment of the automatictransmission 800 is shown. In the eighth embodiment of the automatictransmission 800, the planetary gear sets are longitudinally arranged inthe following order from left to right: 60-40-30-50. Specifically, thefourth planetary gear set 60 is disposed adjacent the first or front endwall 22 in the first position FF, the second compound planetary gear set40 is disposed adjacent the fourth planetary gear set 60 in the secondposition SM, the first planetary gear set 30 is disposed adjacent thesecond compound planetary gear set 40 in the third position TM and thethird planetary gear set 50 is disposed adjacent the second or rear endwall 24 in the fourth position RF. The torque transmitting devices areintentionally located within specific Zones in order to provideadvantages in overall transmission size, packaging efficiency, andreduced manufacturing complexity. In the eighth embodiment automatictransmission 800 shown in FIG. 10A, the first clutch 82 and the secondclutch 84 are disposed in Zone D, the third clutch 86 is disposed inZone B and the first brake 92 and the second brake 94 are disposed inZone A.

However, the eighth embodiment of the automatic transmission 800includes other arrangements where the first clutch 82, the second clutch84, the third clutch 86, the first brake 92 and the second brake 94 aredisposed in other Zones. The feasible locations of the first clutch 82,the second clutch 84, the third clutch 86, the first brake 92 and thesecond brake 94 relative to the Zones are illustrated in the chart shownin FIG. 10B. An “X” in the chart indicates that the eighth embodiment ofthe automatic transmission 800 comprehends locating the first clutch 82,the second clutch 84, the third clutch 86, the first brake 92 and thesecond brake 94 in the referenced Zone.

The description of the invention is merely exemplary in nature andvariations that do not depart from the gist of the invention areintended to be within the scope of the invention. Such variations arenot to be regarded as a departure from the spirit and scope of theinvention.

1. An automatic transmission comprising: an input member; an outputmember; a transmission housing having a first wall, a second wall and athird wall extending between said first and said second walls; a first,a second, a third and a fourth planetary gear assembly disposed withinsaid transmission housing, wherein said second planetary gear assemblyis adjacent said first wall, said third planetary gear assembly isadjacent said second planetary gear assembly, said fourth planetary gearassembly is adjacent said third planetary gear assembly and said firstplanetary gear assembly is between said fourth planetary gear assemblyand said second wall, each of said planetary gear assemblies including asun gear member, a ring gear member and a planet carrier membersupporting a plurality of planet gears meshing with said sun gear memberand said ring gear member, wherein said input member is coupled to saidplanet carrier of said first planetary gear assembly, said output memberis coupled to said planet carrier of said third planetary gear assembly,said ring gear member of said third planetary gear assembly is coupledto said planet carrier of said fourth planetary gear assembly, said sungear member of said first planetary gear assembly is coupled to said sungear member of said fourth planetary gear assembly, said sun gear memberof said second planetary gear assembly is coupled to said sun gearmember of said third planetary gear assembly and said ring gear memberof said first planetary gear assembly is coupled to said planet carrierof said second planetary gear assembly, wherein said transmissionhousing has a first area radially inward from an outer periphery of saidplanetary gear assemblies and axially bounded by said first wall andsaid second planetary gear assembly, a second area radially inward fromsaid outer periphery of said planetary gear assemblies and axiallybounded by said second and said third planetary gear assemblies, a thirdarea radially inward from said outer periphery of said planetary gearassemblies and axially bounded by said third and said fourth planetarygear assemblies, a fourth area radially inward from said outer peripheryof said planetary gear assemblies and axially bounded by said fourth andsaid first planetary gear assemblies, a fifth area radially inward fromsaid outer periphery of said planetary gear assemblies and axiallybounded by said first planetary gear assembly and said second wall, anda sixth area between said outer periphery of said planetary gearassemblies and said third wall and axially bounded by said first walland said second wall; a first clutch selectively engageable between saidplanet carrier of said first planetary gear assembly and said sun gearmember of said second planetary gear assembly; a second clutchselectively engageable between said sun gear member of said secondplanetary gear assembly and said planet carrier of said second planetarygear assembly; a third clutch selectively engageable between said ringgear member of said second planetary gear assembly and said ring gearmember of said third planetary gear assembly; a first brake selectivelyengageable between said sun gear member of said fourth planetary gearassembly and said transmission housing; and a second brake selectivelyengageable between said ring gear member of said fourth planetary gearassembly and said transmission housing, wherein said first clutch islocated in one of said first, second and sixth areas, said second clutchis located in one of said first, second and sixth areas, said thirdclutch is located in one of said second, third, fourth and sixth areas,said first brake is located in one of said fifth and sixth areas andsaid second brake is located in one of said third, fourth, fifth andsixth areas, and wherein said clutches and brakes are selectivelyengageable to establish at least eight forward speed ratios and onereverse speed ratio between said input member and said output member. 2.The automatic transmission of claim 1 wherein at least one of said firstclutch and said second clutch is located in said first area.
 3. Theautomatic transmission of claim 1 wherein at least one of said firstclutch, said second clutch and said third clutch is located in saidsecond area.
 4. The automatic transmission of claim 1 wherein at leastone of said third clutch and said second brake is located in said thirdarea.
 5. The automatic transmission of claim 1 wherein at least one ofsaid third clutch and said second brake is located in said fourth area.6. The automatic transmission of claim 1 wherein at least one of saidfirst brake and said second brake is located in said fifth area.
 7. Theautomatic transmission of claim 1 wherein at least one of said firstclutch, said second clutch, said third clutch, said first brake and saidsecond brake is located in said sixth area.
 8. The automatictransmission of claim 1 wherein said first, said third and said fourthplanetary gear assemblies are simple and said second planetary gearassembly is compound.
 9. The automatic transmission of claim 1 whereinsaid first brake is located in said fifth area.
 10. The automatictransmission of claim 1 wherein said first brake is located in saidsixth area.
 11. The automatic transmission of claim 1 wherein saidsecond brake is located in said fifth area.
 12. The automatictransmission of claim 1 wherein said first clutch is located in saidfirst area.
 13. The automatic transmission of claim 1 wherein said firstclutch is located in said second area.
 14. The automatic transmission ofclaim 1 wherein said first clutch is located in said sixth area.
 15. Theautomatic transmission of claim 1 wherein said second clutch is locatedin said first area.
 16. The automatic transmission of claim 1 whereinsaid second clutch is located in said second area.
 17. The automatictransmission of claim 1 wherein said second clutch is located in saidsixth area.
 18. The automatic transmission of claim 1 wherein said thirdclutch is located in said second area.
 19. The automatic transmission ofclaim 1 wherein said third clutch is located in said sixth area.
 20. Anautomatic transmission comprising: an input member; an output member; atransmission housing having a first wall, a second wall and a third wallextending between said first and said second walls; a first, a second, athird and a fourth planetary gear assembly disposed within saidtransmission housing, wherein said second planetary gear assembly isadjacent said first wall, said third planetary gear assembly is adjacentsaid second planetary gear assembly, said fourth planetary gear assemblyis adjacent said third planetary gear assembly and said first planetarygear assembly is between said fourth planetary gear assembly and saidsecond wall, each of said planetary gear assemblies including a sun gearmember, a ring gear member and a planet carrier member supporting aplurality of planet gears meshing with said sun gear member and saidring gear member, wherein said input member is coupled to said planetcarrier of said first planetary gear assembly, said output member iscoupled to said planet carrier of said third planetary gear assembly,said ring gear member of said third planetary gear assembly is coupledto said planet carrier of said fourth planetary gear assembly, said sungear member of said first planetary gear assembly is coupled to said sungear member of said fourth planetary gear assembly, said sun gear memberof said second planetary gear assembly is coupled to said sun gearmember of said third planetary gear assembly and said ring gear memberof said first planetary gear assembly is coupled to said planet carrierof said second planetary gear assembly, wherein said transmissionhousing has a first area radially inward from an outer periphery of saidplanetary gear assemblies and axially bounded by said first wall andsaid second planetary gear assembly, a second area radially inward fromsaid outer periphery of said planetary gear assemblies and axiallybounded by said second and said third planetary gear assemblies, a thirdarea radially inward from said outer periphery of said planetary gearassemblies and axially bounded by said third and said fourth planetarygear assemblies, a fourth area radially inward from said outer peripheryof said planetary gear assemblies and axially bounded by said fourth andsaid first planetary gear assemblies, a fifth area radially inward fromsaid outer periphery of said planetary gear assemblies and axiallybounded by said first planetary gear assembly and said second wall, anda sixth area between said outer periphery of said planetary gearassemblies and said third wall and axially bounded by said first walland said second wall; a first clutch selectively engageable between saidplanet carrier of said first planetary gear assembly and said sun gearmember of said second planetary gear assembly; a second clutchselectively engageable between said sun gear member of said secondplanetary gear assembly and said planet carrier of said second planetarygear assembly; a third clutch selectively engageable between said ringgear member of said second planetary gear assembly and said ring gearmember of said third planetary gear assembly; a first brake selectivelyengageable between said sun gear member of said fourth planetary gearassembly and said transmission housing; and a second brake selectivelyengageable between said ring gear member of said fourth planetary gearassembly and said transmission housing, wherein said first clutch islocated in said first area, said second clutch is located in said firstarea, said third clutch is located at least partially in at least one ofsaid second and sixth areas, said first brake is located in one of saidfifth and sixth areas and said second brake is located in said fiftharea, and wherein said clutches and brakes are selectively engageable toestablish at least eight forward speed ratios and one reverse speedratio between said input member and said output member.